ATL: Ex INVEST 91L - Discussion (0/0)

[cycloneye]

The dead end.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sat Sep 6 2025

For the North Atlantic...Caribbean Sea and the Gulf of America:

Tropical Atlantic:
A tropical wave over the central tropical Atlantic is producing a
limited amount of shower activity. Development of this system is
not expected while the system moves westward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...near 0 percent.

$$
Forecaster Cangialosi/Kelly

[emeraldislenc]

Major model bust! I guess sometimes it happens!

[StormWeather]

Major model bust! I guess sometimes it happens!

Welp, we have completed the biggest bust in awhile.

[Coolcruiseman]

Major model bust! I guess sometimes it happens!

Welp, we have completed the biggest bust in awhile.

Is it a bust though if it taps into the Amazon moisture around 50W and then proceeds to form? Perhaps the models were just extremely early on developing this wave.

[emeraldislenc]

Only time will tell!

[StormWeather]

Major model bust! I guess sometimes it happens!

Welp, we have completed the biggest bust in awhile.

Is it a bust though if it taps into the Amazon moisture around 50W and then proceeds to form? Perhaps the models were just extremely early on developing this wave.

Maybe, maybe not! We will see.

[sasha_B]

Major model bust! I guess sometimes it happens!

Welp, we have completed the biggest bust in awhile.

A major bust indeed. I've looked over the annual verification stats for Atlantic Invest areas that have been given a 90% chance of formation on an NHC outlook, and the miss rate is well under 10% - in fact, it's 0% for some years this decade. It happens, but it sure is unusual.

[Teban54]

The bizarre thing with 91L is that every single model - all operational models, and both GFS and Euro ensembles - showed nearly unanimous support for days. For most other model busts, either one or two models weren't enthusiastic (often Euro or CMC), or ensemble support had always been lackluster in spite of the operationals.

HMON was probably the only model that never showed development at all. Honorable mention for HAFS-A and HAFS-B, which had weak TS at best for lead times when even ECMWF had strong TS or Cat 1.

[cycloneye]

The bizarre thing with 91L is that every single model - all operational models, and both GFS and Euro ensembles - showed nearly unanimous support for days. For most other model busts, either one or two models weren't enthusiastic (often Euro or CMC), or ensemble support had always been lackluster in spite of the operationals.

HMON was probably the only model that never showed development at all. Honorable mention for HAFS-A and HAFS-B, which had weak TS at best for lead times when even ECMWF had strong TS or Cat 1.

Also the Euro AIFS did not had development.

[cycloneye]

One of many memes that are running on social media.

[LarryWx]

The bizarre thing with 91L is that every single model - all operational models, and both GFS and Euro ensembles - showed nearly unanimous support for days. For most other model busts, either one or two models weren't enthusiastic (often Euro or CMC), or ensemble support had always been lackluster in spite of the operationals.

HMON was probably the only model that never showed development at all. Honorable mention for HAFS-A and HAFS-B, which had weak TS at best for lead times when even ECMWF had strong TS or Cat 1.

Also the Euro AIFS did not had development.

Also, another honorable mention is imho earned by both the GFS and UKMET. Please see below.

8/24 12Z JMA has it
8/25 12Z UK first has a TD about when most non-JMA other than GFS first had it; JMA still has it
8/26 0Z UK drops it and GFS still doesn’t have it
8/26 12Z UK/GFS don’t have it. CMC/Euro dropped it. JMA still has it.
8/27 0Z and 12Z: mostly quiet on models except 12Z JMA
8/28 0Z UK gets it back for 1st time after 4 runs without it with a minimal TS but the others have no TC
8/28 12Z UK again has a TS; GFS finally has it and as a H! JMA drops it after 4 days
8/29 0Z UK again has a TS. Don’t have the others.
8/29 12Z: don’t have handy
8/30 0Z UK has just a TD. Don’t see others.
8/30 12Z UK/GFS/Icon have a TD that dissipates quickly. CMC just a weak low. Euro had a TD that moves to off of NC.
8/31 0Z I don’t have
8/31 12Z much more active than 8/30 12Z: Euro MH, GFS H, Icon TS, JMA TD, CMC just a TD that dissipates, UK drops it.
9/1 0Z similar
9/1 12Z strongest yet with H for Euro, GFS, Icon, and CMC; JMA has a TD and UK again has no TC for 3rd run in a row
9/2 0Z UK has it back as a TD, but it dissipates at end
9/2 12Z UK drops it again. Icon has a TS and Euro a MH.
9/3 0Z UK back on with a TD.
9/3 12Z UK has a TS while GFS has a MH into SC.
9/4 0Z UK drops it again. GFS/Euro have an H. Icon still has it.
9/4 12Z: UK nothing again. Euro has an MDR TS that dissipates in Caribbean. JMA has a recurving H.
9/5 0Z: UK/Euro nothing. GFS/CMC still have a TC
9/5 12Z: UK/GFS/CMC/Icon no TC. Euro no TC til a TD in subtropics. JMA still has an H.
9/6 0Z no model has a TC. It’s dead, Jim.

Based on the above, my rankings are the following:

-GFS best for waiting 3-4 days after others to have a TC
-UKMET a close 2nd best for having many runs without it, never having anything stronger than a low end TS, and dropping it earlier than others
-Euro/ICON/CMC near tied for 3rd
-JMA worst for being first and also last with it. In addition, several of the runs had a H.

[kevin]

One of the biggest model busts in recent times. Especially since it's a peak season disturbance where even SHIPS and other indicators showed a near-perfect shear and moisture environment. But pretty much all models busted big time.

[otowntiger]

When the models can bust so badly on predicting development that doesn’t happen one might presume that they could very well do the opposite and miss predicting something that does develop. So don’t sleep on something developing out of nowhere that models missed.

[wxman57]

Pretty spectacular model fail across the board on this one. Total ghost storm.

Mainly a GFS model fail.

[GCANE]

I dunno.
That dry slot to west of it is filling in pretty good with mid-level moisture in the last 24hrs as it approaches 50W.
We'll see tomorrow if the pros and models are right or not.

[GCANE]

Actually, convection is firing now in low shear just north of the LL vort.

[DorkyMcDorkface]

Pretty spectacular model fail across the board on this one. Total ghost storm.

Mainly a GFS model fail.

And ICON, and CMC, and Euro early on, and Deepmind...GFS was perhaps the most persistent but let's not act like it was a lone wolf here. Most models had some form of development until the last two days or so. I agree with the other poster in that it was pretty much a universal failure this time around